The present supplementary application has been made necessary by the fact that it is anticipated that a completely changed personnel classification and associated salary increases for technical and clerical personnel will be adopted by the University of Washington. The amount awarded initially was also substantially less than that requested. This would make necessary a significant reduction in personnel and the breaking up of an effective, productive research team. The basic objectives of the research program out-lined in this proposal is to provide quantitative measurements of physiologic variables involved in fluid balance at the capillary level. These include quantitative determinations of the differences in filtration coefficients of arterial and venous capillaries, colloid osmotic pressure of lymph, plasma and tissue fluid in intact unanesthetized bats and studies of interstitial transport of proteins and dyes. Techniques have been developed for measuring oncotic pressure of 1 microleter samples and for obtaining sequential recordings of optical density changes associated with dye diffusion in subcutaneous connective tissue of the bat wing by means of a TV-microdensitometer. The second part of the proposal is aimed at studying mechanics of vascular smooth muscle in the intact unanesthetized animal preparation. In these studies quantitative measurements would be obtained of the mechanics of mammalian smooth muscle contraction such as derivation of relationship between contractile force of the vascular smooth muscle and discharge rate in sympathetic vasoconstrictor fiber. Viscoelastic properties of terminal arteries and arterioles will also be studied in terms of stress-strain and stress-strain rate curves in response to stepwise increase in transmural pressures. Local changes in vasomotor activity associated with exercise in skeletal muscle will also be evaluated, particularly in terms of changes in vasomotor pattern and discrete diameter changes of resistance vessels in skeletal muscle. Changes in skeletal muscle capillary blood flow at rest, immediately following exercise, and during the recovery phase would also be measured and correlated with the results from the studies on skeletal muscle resistance vessels.